SAT height/time problem

At time , a ball was thrown upward from an initial height of 6 feet. Until the hall hit the ground, its height (in feet), after t seconds was given by function h above, in which and are positive constants. If the ball reached its maximum height of 106 ft at , what what the height of the ball, in feet, at time ?

Obviously, this is a downward sloping parabola since it has a maximum.